Measuring device.



Patented Nov. 23, 1909.

J. HOOD.

MEASURING DEVICE.

APPLICATION FILED JULY 20, 1909. 941,253.

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UNIT JOHN HOOD, OF BOSTON, MASSACHUSETTS.

IVIEASURING DEVICE.

Specification of Letters Patent.

Patented Nov. 23, 1909.

Application filed July 20, 1909. Serial No. 508,670.

To all whom "it may concern:

Be it known that I, JOHN H001), a citizen of the United States, and aresident of Bos ton, in the county of Suffolk and State ofMassachusetts, have invented certain new and useful Improvements inMeasuring Devices, of which the following is a description.

The invention relates to a measuring de vice particularly adapted to theuse of dentists. I11 his practice it is often necessary for the dentistto use small definite portions of mercury in the formation of hisamalgams. Ordinarily he arrives at the quantity necessary by guesswork,which results in a waste of materials and an improper proportioning ofthe constituents of the amalgam.

The invention in the present instance has for its object the provisionof a device whereby the exact quantity of mercury necessary for theparticular operation can be readily measured so that a properproportioning of the metals of the amalgamation can be obtained and awaste of materials avoided.

The invention consists in the novel device hereinafter described,pointed out in the appended claim, and illustrated in the accompanyingdrawings.

In the drawings, in which similar reference characters designatecorresponding parts, Figure l is a perspective View of a measuringdevice embodying the invention. Fig. 2 is a vertical sectional view ofthe same.

The cylindrical receptacle 1 of hard rubber, or of other suitablematerial for holding mercury, has a screw-threaded bore that extends theentire length of its interior wall. In this receptacle is the piston 2,also of hard rubber, exteriorly screw-threaded to engage thescrew-threaded bore of the receptacle. Extending vertically through thepiston is the channel 3 opening at its upper end into the cup 4 on thetop of the piston. Just before the channel 3 enters the cup the passage,as at 5, is contracted. Secured in the upper end of the piston is theangular arm 6 forming a pointer extending outside of the receptacle 1parallel with the vertical axis of the device. As the piston is rotatedthe pointer registers with the graduations 7 on the upper edge of therece tacle l.

IVith the receptacle 1 filled, or partly so, with mercury, when thepiston 2 is turned into the same it presses down upon the mercury andforces it through the channel 3 and contracted passage 5 into the cup 4.The contracted passage prevents a too free flow of the mercury throughthe channel. By calibration the graduations 7 are so spaced that acertain definite weight of mercury will be forced into the cup as thepiston is turned so that the ointer travels the distance between two ofthe graduating marks. For a device of the size shown in the drawings thegraduations 7 are spaced so that when the piston is turned to move thepointer from one mark to the next one two grains of mercury will beforced into the cup. By observing the pointer 6 as it passes the marks 7when the piston is turned down into the receptacle, the desired weightof mercury can be measured into the cup, from which it can be turnedinto the receptacle where the amalgam is made.

Having thus described my invention, what I claim and desire to secure byLetters Patent is,

I11 a measuring device, a cylindrical receptacle provided withgraduations and having a screw-threaded bore, a piston exte riorlyscrew-threaded to engage the bore of the receptacle, a cup at the outerend of the piston communicating through the latter with the interior ofthe receptacle, and a pointer on said piston to register with thegraduations on the receptacle as the piston is rotated to force thecontents of the receptacle through the communication through the pistoninto the cup.

In testimony whereof I hereunto aflix my signature in the presence oftwo witnesses.

JOHN HOOD.

Witnesses:

GEORGIA I-I. RILEY, Orrs ATKINSON.

